1. Field of the Invention
The present invention relates to a Bourdon tube pressure gauge, more particularly relates to the sealing of a fastening end of the Bourdon tube with a tube support supporting this or the sealing of a free end of the Bourdon tube with a cap closing it.
2. Description of the Related Art
Conventionally, in a Bourdon tube pressure gauge, for example, as a method of sealing and fixing the fastening end of a Bourdon tube to the tube support, generally the fastening end is inserted into an insertion hole of the tube support, then an opening edge of the insertion hole and the circumferential surface of the fastening end are soldered or otherwise welded together. For reference, see Japanese Patent Application No. 2000-280604 (FIG. 3).
However, in the above-described sealing method, the molten solder or other weld metal penetrates into the clearance between the insertion hole and the inserted tube end by capillary action, but the weld metal has a hard time spreading to the clearance space at the deep end where the tube end is inserted and that cannot be judged visually. When the weld margin (fastening margin) remains only at the opening side of the insertion hole in this way, the tube end is liable to detach from the insertion hole at the time vibration or excessive pressure when the Bourdon tube pressure gauge is actually used.